I understand how you feel, I freak out when I go out and realise I don't have any blades with me, even if I don't plan on using them while out I still feel very unsafe not having them with me.
Maybe you could use this as an oppurtunity to challenge yourself ans see how long you can go for without SIing?
If you think you might cut as soon as you manage to get blades, then maybe try not to buy any until you feel you really have to, as buying some could trigger you to use them even if you don't have any urges (I want to cut when I get new blades or first aid stuff even if I'm not triggered or having urges, so just in case it's the same with you).
Try distracting yourself from thinking about forgetting your blades, I also like Amaryllis's idea
